Random Definition and 1000 Threads

How does lemma 18.2.2 imply the definition?

##\frac{dp}{dt}## is given the name 'force' but ##\frac{dp}{ds}## has no name. I know 'force' is useful for calculations and predicting the future of the system. If 'convenience in calculations' is the reason why some quantities are given names, then I don't see why ##\frac{dp}{ds}## doesn't...

Exactly how does a mouse brain and or body record a shock to mouse feet to mouse sperm cells. If you are familiar with the mouse experiment I find this fantastic, not so much because of what it shows, but because no one cares enough to expand upon it as it invalidates natural selection over a...

For the following random curves for example. Can you really get one derivative equation that can reproduce all of them? How? Or is it multiple individual derivative equation for each unique curve such that the equations that reproduce the following?

Hi all, I am developing a very simple computer game to randomly move a point to on a bound region and check how many steps it takes to have the point landing to a certain place. To make it simple, I assume it is a 1D problem, the point could start on origin or any location on positive x axis...

A paradigm shift for me occurred when, I now realize, that position and momentum are random variables in QM. As such, it does not make any sense to say things like "take the derivative of the position with respect time". Instead QM has the position and momentum operators which operate on the...

Hello, I have this program where you run the JApplet and it makes circles at random. When you click the "Generate" button, it makes another set of random circles. The problem is, it overlaps the previous set of circles. I want the program to get rid of the previous set and I can't figure out...

Hello, I am somewhat new to this forum but have a basic question that I have had for a long time. please excuse it if it is a dumb question. I understand how centrifugal force works - you spin something around and it wants to fly away from the center. And I understand that there are...

Problem: I'm interested in studying the probability of an event involving a random vector. Specifically, I'm interested in (∂/∂a)Pr[X>( (Y-a)/Z )] Where "a" is a non-random parameter and the random vector {X,Y,Z} is distributed Normal( µ, Σ) for µ={0,0,0} and Σ= {{1, 0.5, 0.5}, {0.5, 1, 0}...

Suppose we are talking about a purely classical phenomena (OK, nothing is purely classical, but suppose we consider quantum effects as insignificant, that is, we ignore them). In this context, I came across someone talking about "a particle in chaotic continuous motion as the particle is...

Hello Everyone I have got a question concerning the calculation of the overall energy input in random vehicle vibration tests. I have got different power spectral density levels for different random vehicle vibration tests and would like to compare them with each other concerning the overall...

So let's say I do some measurements and obtain a set of measured values. The measurement is characterized by random errors so by making enough measurements, they approach a normal distribution. In other words, my set of measured values can be approximated by a normal distribution characterized...

Hello, According to the Wikipedia article on random variables: If the above statement is true, then, instead of defining a (real) random variable as a function from a sample space of some probability space to the reals, could we equivalently define it as a subset of ℝ associated with a CDF?

Let K be any Matrix, not necessarily the hamitonian. Is $$e^{-Kt}\left|\psi\right>$$ equal to $$e^{-K\left|\psi\right>t}$$ even if it is not the the eigenvector of K? I think so as i just taylor expand the $$e^{-Kt}$$ out but I want to confirm. In that case can i say that...

Homework Statement Let w(1) = event of a random walk with right drift (p > q, p+q = 1) starting at 1 returns to 0 Let p(w(1)) = probability of w(1) Let S=min{t>=0:wt(1)=0} be the minimum number of steps t a walk starting from 1 hits 0. What is E[S|w(1)]? Homework Equations I know E[S|w(0)] = 0...

On the attachment, I was told my joint pdf was right, but the support was NOT 0<y1y2<1 0<y2<1, so maybe it's right now? Obviously B and C are incorrect, too, since they don't integrate to 1. I'm probably making just a few simple mistakes. Thanks in advance!

I'm currently in first year engineering and I seem to be struggling with Physics, which is not unlikely uncommon. A simple problem I've come across is not doing correct error analysis when writing up lab reports. In my current lab, which is justifying the relationship of angular frequency...

There's this problem that I've been trying to solve. I know the solution for it now but my initial attempt at a solution was wrong and I can't seem to figure out the mistake with my reasoning. I'd appreciate some help with figuring this one out. 1. Homework Statement I have a set of random...

Let ##f(x,y,z)=x^2e^{-x-xy-xz}##, if ##x,y,z>0## and ##f(x,y,z)=0## otherwise. Are the continuous random variables ##x,y,z## independent or not? Intuitively they are not independent. I calculated the marginal density functions: ##f_x(x)=\iint_{\Omega} f(x,y,z) dydz=e^{-x}##...

Homework Statement The probability density function for a random vector ##(X,Y)## is ##f(x,y) = 3x##, when ##0 < y< x < 1##. Calculate the conditional probability P(X> \frac{1}{2} | Y > \frac{1}{3}) Homework Equations Conditional probability: \begin{equation} P(A | B) = \frac{P(A \cap...

It is said that entanglement doesn't violate relativity because there is no information transferred. Ther reasoning being Bob and Alice only get randomness even if there is correlation. But can random energy be transferred as it is still random? For example. Entropy decreasing at one place and...

Homework Statement Let's say you have a number from [-2,4], with X(ζ) = -ζ + 4[/B] Find (a) P([-2,4]) and (b) P({X≤2}) Homework Equations {X = x} = {ζ ∈ S: X(ζ) =x } The Attempt at a Solution It looks like my sample space, S = [-2,4]. (a) For P([-2,4]) {-2 ≤ X ≤ 4} = {ζ ∈ S: -2 ≤ X(ζ) ≤...

This thread was posted and discussed on Physics Overflow, I am re-posting it here to hear other opinions. http://www.physicsoverflow.org/36063/given-decoherence-still-random-quantum-jumps-interpretations? Environmental decoherence explains how the wavefunction of a quantum system q, as a result...

I want to generate very random numbers. There's a few approaches to this, such as the audio input from a de-tuned radio, hooking user input such as mouse movement and hashing the results over a period of time etc.. My idea was to get a cheap Geiger Counter and just leave it monitoring background...

I used to have a bunch of these on - ahem VHS,,, This was one that I think shows - all bets are off on trying to predict ground fault current... Even the firemen, keeping their distance (not enough IMO), are almost fooled as the arc stops around 1:42.. nope.

Hello all, Suppose I have the following summation ##X=\sum_{k=1}^KX_k## where the ##\{X_k\}## are independent and identically distributed random variables with CDF and PDF of ##F_{X_k}(x)## and ##f_{X_k}(x)##, respectively. How can I find the CDF of ##X##? Thanks in advance

I heard from many sources that quantummechanics is purely random in nature. Has this been demonstrated? If so, what is the proof?

Homework Statement Suppose that the number of asbestos particles in a sam- ple of 1 squared centimeter of dust is a Poisson random variable with a mean of 1000. What is the probability that 10 squared cen- timeters of dust contains more than 10,000 particles? Homework Equations E(aX+b) =...

Suppose we have a source of polarization-entangled photons, that fires pairs of photons in opposite directions at two detectors with orientation-adjustable polarizationfilters in front of them. Obviously, there is a correlation between the orientation of the respective filters and the joint...

Hi, I need a textbook for a graduate electrical engineering course 'Random Processes'. Here is the course description "Elements of probability theory, random variables, and stochastic processes." The recommended textbook is https://www.amazon.com/dp/0131471228/?tag=pfamazon01-20 Any...

I have a model in which, for each store, predicted revenues are perturbed by a multiplicative shock: R = e^\eta r where r is predicted and R is observed. \eta is mean zero. I can find \eta as follows: \ln( r) - \ln( R) = \eta . I'm summing the squares of the \eta's. However, there are...

Hello, could anyone please explain me some logic or derivation behind the approximation: Found it in the Hull Derivatives book without further explanation. Thanks for help

Time to start a new thread. Here is the last page of part 5. https://www.physicsforums.com/threads/random-thoughts-part-5.851969/page-134

Homework Statement Consider the bivariate vector random variable ##(X,Y)^T## which has the probability density function $$f_{X,Y}(x,y) = \theta xe^{-x(y+\theta)}, \quad x\geq 0, y\geq 0 \; \; \text{and} \; \; \theta > 0.$$ I have shown that the marginal distribution of ##X## is ##f_X(x|\theta)...

If the odds of randomly picking a 3 digit number correctly are 1000-1, then what are the odds of that same number being picked 4 times in 364 picks?

This question is driving me crazy. According to the textbook, the answer is 7/15, but I get 2/5. If anyone can tell me where I am going wrong I would be much obliged Here is the question Six fuses, of which two are defective and four are good, are to be tested one after another in random...

Hi All Im hoping I am in the right area to ask this?!? Im looking for someones help. Is there a standard methodology or known equation for generating a random alpha numeric serial or incremental, which does not allow two characters to be used in sequence to each other which are near each other...

Given a continuous random vector (X,Y) with a joint density function In order to check whether it is indeed a joint density ƒ(x,y) the method is to check if ∫∫ƒ(x,y)dxdy=1 where the integrals limits follow the bounds of x and y. However, is it the case that if given an arbitrary discrete random...

Hello. I recall that the probability of generating a particular real number (in a bounded or unbounded interval) is exactly zero. If I keep generating reals for a limited amount of time, can I get a number more than once? About the computer, I know that the amount of different values the type...

So which method works better for random number generation(in terms of flatter frequency spectrum): transistor breakdown or Zener noise? I want to know whether to use a Zener diode or a Transistor when building a white noise generator. And FTR I intend to use Germanium because of its higher...

Ok, for the switch-on voltage of a red LED I have the readings as follows, all in volts: 1.45, 1.46, 1.46, 1.44, 1.45. The mean of these readings, in volts, is 1.45 (I rounded up to 2 decimal places as my scale reading uncertainty was +/-0.01V, and my teacher told me to round them up since to...

I create this thread to continue discussion with @jim hardy and @WWGD started elsewhere https://www.physicsforums.com/threads/any-popular-non-biased-and-reputable-sources-of-politics.827409/page-4#post-5422569 Any topic concerning computers and internet can be discussed here I don't know, but...

I got this probability question as homework, but I got very confused as I didn't know if I should calculate the balls in the 2 boxes as whole or if I should calculate the probability of the first box then add the probability of the second. Any help is appreciated. Thanks.Here is the question...

Is quantification, such as for instance with the build op of an interference pattern by individual photons, the measuring of quantum spin, or the measuring of polarized photons through a polarisation filter actually, really random, or is it possible that it might be pseudo-random?

Thank you for your time, I really appreciate it I have no idea where to even begin

A continuous random variable x has the following probability function: f(X)=(X+1)/8 -1<=X<=3 0 Otherwise 1. Find the Pr(X<=2) 2. Find the mean of X

$p(x) ={p}^{x}*{(1-p)}^{1-x}$ for $x=0.1$ $0$ otherwise Where $p$ is such that $0<=p<=1$ Question: Find the mean and variance of $X

I'm dabbling with regression (In excel), but I'm stuck because my residual plot is not normal. I have 2 variables: age, and gender(0 or 1). I regress it in excel and also plot the residuals, it is not random. In general, how do I solve this issue? If it matters, the result of my raw...

Hi All, Looking for Advice on taking Random Signals Class in the summer, I am EE student, Is it very difficult? very challenging or demanding?. I have taken classes in the summer in a community college and I have done OK(B), however I am a little unsure about this one. I work full time and have...

1.Above sentence means in 1074 mutations(Events) just one of them could make a functional protein and that mutation is beneficial? 2.Is above sentence similar to "Hoyle's calculation of the Odds of Life", thus the criticism against Hoyle's idea can apply to above sentence? Like this: